# Centrifugal and centripetal force question: race-car and banked curve question

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P: 41,486
 Quote by zeion First of all, I don't really understand centrifugal force. Centripetal force is for when an object has uniform circular motion, right? How is it affected by centrifugal force?
All you need is centripetal force. (Centrifugal force is a "fictitious" force used when analyzing things from an accelerating frame--no need for that here.)

As far as this problem goes, you are not given enough information to solve it. Can you please tell me the textbook this is from and the problem number. (In case I have the textbook.)
P: 467
 Quote by Doc Al As far as this problem goes, you are not given enough information to solve it. Can you please tell me the textbook this is from and the problem number. (In case I have the textbook.)
This is from an independent learning course from the Independent Learning Center in Ontario. It's in Lesson 4 of Unit 1.

What other information do I need to solve it?

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P: 41,486
Centrifugal and centripetal force question: race-car and banked curve question

 Quote by zeion This is from an independent learning course from the Independent Learning Center in Ontario. It's in Lesson 4 of Unit 1.
I don't have that one. This exact problem has cropped up before. The problem is flawed.

 What other information do I need to solve it?
Generally a road is banked for a given speed so that a car can make the turn without needing any friction. You are not given any information about the speed for which the curve is designed.
 P: 467 Can i sue them for giving flawed questions?
 P: 3 you better read the contents before you go to this question. firstly, you have to draw a FBD. a)Fn=Fg/cos15 Fn=14711N Fc=sin15 Fc=14711*sin15 Fc=3807N r=Fc/mv^2 r=6.72*10^4m b) a=Fc/m a=2.626m/s^2
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P: 41,486
 Quote by wmhcan you better read the contents before you go to this question. firstly, you have to draw a FBD. a)Fn=Fg/cos15 Fn=14711N Fc=sin15 Fc=14711*sin15 Fc=3807N r=Fc/mv^2 r=6.72*10^4m
On what basis did you calculate r? You don't know the speed for which the track is banked. (You cannot assume that it's banked for the given speed of 225 km/h.)

(And your equation for r is upside down.)
 P: 18 ok so i just did that 2 weeks ago, got full marks for it XD. so for a) u use v= sqrt ( g r tan(angle)) v= velocity g= earth's gravitational force v= 225km/h = 62.5 m/s angle= 15 m= 1450kg so i'm not going to draw a FBD, you do that yourself, now continueing with a) v^2= g r tan(angle) 62.5^2=9.8 r tan 15 r=3906.25 / 2.63 r=1485.3m b) ac = centripetal acceleration ac= v^2 / r , meh i'm not going to write the rest of the problem to this because i believe you can finish this. solution = 2.63 m/s^2 c) Fs max = m g sin(angle) Fs max= magnitude of the force of static friction solution = 3677.8N d) (can't make the mu symbol for coefficient of friction >< ) mu s = tan (angle) mu s = tan 15 mu s = 0.268 you're very welcome, please send me a fruit basket for x-mas =D
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P: 41,486
 Quote by the_morbidus so for a) u use v= sqrt ( g r tan(angle)) v= velocity g= earth's gravitational force v= 225km/h = 62.5 m/s angle= 15 m= 1450kg so i'm not going to draw a FBD, you do that yourself, now continueing with a) v^2= g r tan(angle) 62.5^2=9.8 r tan 15 r=3906.25 / 2.63 r=1485.3m
That equation assumes that the track is banked for the given speed and angle and zero friction.

 P: 18 darn it i really wanted that fruit basket XD . well i say we should complain to the teachers, after all im only the poor little student that is using the equations that are given in the book >.> . but i did get 3/3 marks for that question, therefore i assume it was meant to be a flawed example for the simple purpose of teaching the student?
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P: 41,486
 Quote by the_morbidus but i did get 3/3 marks for that question, therefore i assume it was meant to be a flawed example for the simple purpose of teaching the student?
Ask your instructor to explain how he did part a. (Do you understand how the equation you used is derived?)
 P: 18 yes i understand how the equation was obtained, but i'm in the process of learning so i might think i know but i might not know at all. anyways what books on classical physics for around grade 12 and perhaps beyond would you recommend that explain it well and are reasonable to understand??
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P: 41,486
 Quote by the_morbidus yes i understand how the equation was obtained, but i'm in the process of learning so i might think i know but i might not know at all.